Process for hardening light-sensitive photographic layers containing gelatine

ABSTRACT

COLORLESS HALOGENO PYRIMIDINES AND HALOGENO-1,3,5-TRIAZINES CONTAINING NO FREE ACIDIC GROUPS ARE USED FOR HARDENING LIGHT SENSITIVE GELATINE LAYERS.

United States Patent Office 3,701,664 Patented Oct. 31, 1972 US. Cl.96-111 12 Claims ABSTRACT OF THE DISCLOSURE Colorless halogenopyrimidines and halogeno-1,3,5-triazines containing no free acidicgroups are used for hardening light sensitive gelatine layers.

This application is a continuation of application Ser. No. 796,570 filedFeb. 4, 1969, now abandoned.

The present invention provides a process for hardening light-sensitivephotographic layers containing gelatine, wherein the hardening agentused is a colourless compound which is free from acidic groups andcontains at least one six-membered heterocycle comprising three or fourcarbon atoms and three or two nitrogen atoms, at least one halogen atomlinked with a carbon atom of the 6-membered ring and at least oneorganic residue linked with the heterocycle directly or through anoxygen or a sulphur atom.

Suitable compounds are, for example, pyridazine, pyrimidines, pyrazinesor 1,3,5-triazines. The compounds of the following general formulae maybe mentioned:

Il Chalogen 0:0 haloger i halogen halogen-0 C--halogen C=C Iti l ialogen(3) halagen N R C O-halogen halogen halogen 2 halogen-C C-halogenhalogen R1C CH alogen (6) halogen halogen-C CH (7) halogen N-- halogen-CC-R N=CH ( halogen halogen I OH=('3 R1 halogen halogen N 1 C=C in whichR represents an organic residue which is free from acidic groups. R maybe linked with the heterocyclic 6-membered ring directly or through anoxygen 01' a sulphur atom. In the case of the Formula 9 the organicresidue R converts a dihalogenopyrazine is a dihalogenoquinoxaline ring.5

Those compounds are preferred which contain at least onehalogeno1,3,5-triazine or halogenopyrimidine residue. Quite generally,compounds for example, containing bromine atoms or especially chlorineatoms linked with the six-membered heterocycle may be used.

Among the halogeno- 1,3,5 -triazines and halogenopyrimidines specialmention must be made of the compounds of the formulae a. N\ Chalogenhalogen and HC-N R C C-halogen (I halogen in which R, has the abovemeaning. The residue R is advantageously a hydrogcarbon residue which isunsubstituted or substituted by halogen atoms, alkyl, alkoxy, aryl,arylory, aralkyl, aralkoxy, nitrile, hydroxyl, carbalkoxy, alkenyl,secondary or tertiary amino groups and/or a further 1,3,5-triazine orpyrimidine residue, the said hydrocarbon residue being bound to thetriazine or pyrimidine ring directly or through an oxygen or a sulphuratom. Aliphatic or araliphatic hydrocarbon residues, or a hydrocarbonresidue of the benzene or naphthalene series, are preferred. Forexample, two dichlorotriazines may be linked together through an organicresidue which in this case is, for example, an alkylene residue which islinked with the triazine residues directly or through an oxygen or asulphur atom.

The organic residues R in the Formulae 1 to 10 like the heterocycliccompound itself must be free from acidic groups and may, for example, bea residue of the following formulae OCH2CHzCHa 3. g

and the following pyrimidines may be reacted with gelatine:

The heterocyclic compounds required in the present process can bemanufactured by known methods.

Thus, for example, compounds of the above-mentioned kind in which theorganic residues are linked with the six-membered heterocycle throughoxygen atoms may be manufactured from easily accessible startingmaterials by simple processes. Cyanuric chloride may be reacted, forexample, in an aqueous solution in the presence of sodium hydrogencarbonate with the corresponding alcohol (I. Am. Chem. Soc. 73, p. 2989(1951)), or a mixture of cyanuric chloride and acetone may be reactedwith the corresponding alcohol in the presence of collidine. Thecorresponding mercapto compounds are accessible in an analogous manner(Recueil des travaux chimiques des Pays-Bas 78, p. 967 (1959)).Compounds in which the organic residues are linked directly with thesix-membered heterocycle are most advantageously manufactured byreacting cyanuric chloride with the corresponding Grignard compound, orfrom trichloromethylisocyanide dichloride and the corresponding amidines(Helv. Chim. Acta 33, p. 1365 (1950); Journal of the Chemical Society1965, p. 1113; German patent specification No. 1,178,437). The compoundof the Formula 31 may be manufactured as described in Collect.Czechoslov. Chem. Commun. 31, pp. 3990-4001 (1966).

The halogen atoms of the compounds of 'Formulae 1 to 32 react with thehydroxyl, mercapto, amino or imino groups of gelatine with formation ofhomopolar bonds. In general, the reaction between gelatine and thesecompounds proceeds smoothly in the usual manner. As a rule, they aresufficently soluble in water or in water-miscible, photographicallyinactive, organic solvents for example acetone, methanol, ethanol ordimethylformamide. Thus, for example, it is essential that thesecompounds can be dispersed in 0.1 to aqueous gelatine solutions in sucha manner that they do not settle out in crystalline form.

In most cases it sufiices to add the products to be used according tothis invention in the form of a solution in a water-miscible solvent toan aqueous gelatine solution with vigorous stirring, although theconventional dispersing methods by means of kneading and/or shearing orultra-sound may also be used.

Thus, for example, a solution of the hardener in water, ethanol ormethanol may be added to the gelatine at room temperature or a slightlyhigher temperature and the gelatine containing silver halide and/orother materials needed for producing photographic images poured over abase in the usual manner to form a layer which, if desired, may bedried. The layer can then be left for a certain time, for example up to18 hours, at an elevated temperature or at room temperature wherebyhardening sets in rapidly and progressively; the melting point of thegelatine rises considerably, for example by 25 to 60 C. The amount ofhydrohalic acid released during the hardening is, in view of the actualproportions of the two reactants, so small that it is completelybulfered by the excess of gelatine present so that the pH value of thegelatine is practically unaffected by the hardener.

The desired degree of hardening can be advantageously controlled byvarying the amount of hardener used and is advantageously from 0.25 to5% referred to the weight of dry gelatine. The hardening of the gelatineis obviously caused by an extensive cross-linking. The hardening affectsneither the photographic properties of the photosensitive layers nor thereactivity of dye couplers or dyes.

A special advantage of the hardeners to be used in the present processis that when used in a low concentration they impart an adequate degreeof hardness to the gelatine layers even after 18 to 24 hours so that thequality of the cast layers can be inspected by a test processingimmediately after their manufacture even at an elevated temperature orin vigorous treatment baths.

The compounds of the Formulae l to 32 are equally suitable for hardeninginterlayers in multilayer materials, for example separating layers,filter layers, coatings, substrations or baryta coatings.

The compounds having a relatively low molecular weight, for examplecompounds of the Formulae 11 to 32 may, by virtue of their gooddiffusibility in a multilayer material, be added only to the interlayersand a hardening of the vicinal silver halide layers effected bydilfusion. However, with increasing molecular Weight, comparablecompounds are less diffusible when used in photographic layers. In themanufacture of multilayer materials this property has severalconsiderable advantages. It is known that when casting multilayers,either wet-on-solidified or wet-on-dry, the hardener always diffusesfrom the upper into the lower layers so that the lower layers arehardened more extensively than those above. As a result of suchdifferential hardening the layers detach themselves or wrinkles appearwhen such materials are being developed. The use of sluggishly diffusinghardeners prevents this harmful migration of the hardener in multilayermaterials. On the other hand, such sluggishly diffusing compounds alsomake it possible to harden each individual layer difierently by varyingthe quantity of hardener used; this is of importance, for example, forthe manufacture of multilayer materials in which the emulsion layerscontain dyes or dye formers. Additives of this kind can cause adissimilar lowering of the melting points of the gelatine layers, andthis can be compensated by suitably increasing the amount of hardeneradded to the individual layer. The low diffusing hardeners of thecomposition indicated also bring about a more extensive hardening of theprotective coating, the so-called overcast, than of the emulsion layersunderneath it without affecting the hardening of the latter.

The following examples illustrate the invention. Unless otherwiseindicated, parts and percentages are by weight.

EXAMPLE 1 10 ml. of a 10% aqueous gelatine solution are mixed with 0.6ml. of a 1% methanolic solution of the compound of the Formula 17. Thesolution is poured over a plate of glass 18 x 24 cm. and this plate isdried in circulating air at 32 C. After 24 hours storage the meltingpoint is above C.

EXAMPLE 2 1 kg. of silver bromide emulsion containing 10% of gelatine ismixed with 50 ml. of a 1% acetone solution of the compound of theFormula 15, cast on a film base and dried. After 15 hours storage at 43C. (relative atmospheric humidity 69%) the layer melts above 90 C.

The results obtained by hardening aqueous gelatine with the compounds ofthe Formulae 11, to 25, 27 to 32 are listed in the following table.

8 being bound to said compound directly or by an oxygen or sulfur atom,and halogen is chlorine or bromine.

5. A process as claimed in claim 1, which comprises Percent Meltingpoint in C. afterreferred to 1% solution Example Formula gelatine in- 24hrs. 48 hrs. 96 hrs.

17 0. 6 Methanol-- 90 90 90 15 0. 5 Acetone 90 90 90 11 0. 6 Methanol 8890 95 16 0. 6 d 90 90 95 18 0. 6 90 90 90 19 0. 6 70 95 95 21 0. 6 70 8590 22 0. 6 40 47 86 23 5. 6 95 95 95 24 0. 6 95 95 95 25 0. 6 95 95 9520 0. 6 70 95 96 27 5. 6 95 95 95 28 5. 6 94 95 95 29 5. 6 95 95 95 305. 5 do 95 95 95 31 5. 6 Methan0l 95 95 95 32 5.6 Acetone..- 95 95 95 1After 15 hours at 43 C. (relative atmospheric humidity 69%). 1 At 43 0.(relative humidity 69%). After 5 hours at 43 0. (relative humidity 69%).

We claim: 1. A process for hardening silver halide light-sensitivephotographic layers containing gelatine, which comprises incorporatingin the gelatine as a hardening agent 0.25 to.

5%, referred to the weight of the dry gelatine of a colorless compoundfree from acidic groups selected from the group consisting of1,3,5-triazine, pyrimidine, pyridazine and pyrazine having at least onechlorine or bromine atom linked with a carbon atom of said compound andat least one hydrocarbon radical which is unsubstituted or substitutedby halogen, alkyl, alkoxy, aryl, aryloxy, aralkyl, aralkoxy, nitrile,hydroxyl, carbalkoxy, alkenyl, secondary or tertiary amino and/or afurther 1,3,5-triazine or pyrimidine radical, the said hydrocarbonradical being bound to a carbon atom of said compound directly or by anoxygen or sulfur atom.

2. A process as claimed in claim 1, which comprises incorporating in thegelatine a hardening agent selected from bromo or chloro-1,3,5-triazineor a chloro or bromo pyrimidine having at least one hydrocarbon radicalwhich is unsubstituted or substituted by halogen, alkyl, alkoxy, aryl,aryloxy, aralkyl, aralkoxy, nitrile, hydroxyl, carbalkoxy, alkenyl,secondary or tertiary amino and/or a further 1,3,5-triazine orpyrimidine radical, the hydrocarbon radical being bound to a carbon atomof said compound directly or by an oxygen or a sulfur atom.

3. A process as claimed in claim 1 which comprises incorporating in thegelatine a hardening compound selected from bromo orchloro-l,3,5-triazine and bromoor chloro-pyrimidine said compound havingas a substituent at least one of cycloalkyl, cyano, phenyl, naphthyl,

thiofuranyl, alkenyl, alkynyl, alkyl or alkyl substituted by chloro,hydroxyl, alkoxy, hydroxyalkoxy, phenyl ordichloro-1,3,S-triazinyl-4-oxyalkylene, said substituent being bound toa carbon atom of the triazine or pyrimidine group either directly or byan oxygen or sulfur atom.

4. A process as claimed in claim 1, which comprises incorporating in thegelatine as a hardening agent a compound of the formula halogen whereinR represents a hydrocarbon radical which is unsubstituted or substitutedby halogen, alkyl, alkoxy, aryl, aryloxy, aralkyl, aralkoxy, nitrile,hydroxyl, carbalkoxy, alkenyl, secondary or tertiary amino and/or afurther 1,3, S-triazine or pyrimidine radical, said hydrocarbon radicalincorporating in the gelatine as a hardening agent a compound of theformula R C C-halogen alogen wherein R represents a hydrocarbon radicalwhich is unsubstituted or substituted by halogen, alkyl, alkoxy, aryl,aryloxy, aralkyl, aralkoxy, nitrile, hydroxy, carbalkoxy, alkenyl,secondary or tertiary amino and/or a further 1,3,5-triazine orpyrimidine radical, said hydrocarbon radical being bound to saidcompound directly or by an oxygen or sulfur atom, and halogen ischlorine or bromine.

6. A process as claimed in claim 1, which comprises incorporating in thegelatine as a hardening agent a compound of the formula C :N t.

wherein R represents a hydrocarbon radical bound to the triazine ringdirectly or by an oxygen or a sulfur atom and carrying as a substituentat least one member selected from the group consisting of a halogenatom, an alkoxy group, an aralkyl group, an aralkoxy group, a nitrilegroup, a hydroxyl group, a carbalkoxy group an alkenyl group, asecondary amino group, a tertiary amino group and a further1,3,5-triazine ring.

8. A process as claimed in claim 1, which comprises incorporating in thegelatine .as a hardening agent the compound of the formula 9. A processas claimed in claim 1, which comprises incorporating in the gelatine asa hardening agent the compound of the formula 10. A process as claimedin claim 1, which comprises incorporating in the gelatine as a hardeningagent the compound of the formula 11. A process as claimed in claim 1,which comprises incorporating in the gelatine as a hardening agent thecompound of the formula Cl X K N C-O-CHr-CHECH wherein m and n eachrepresents a whole number, m being at most 2 and n at most 4.

References Cited UNITED STATES PATENTS 3,138,461 6/1964 Ryan 961113,288,775 11/1966 Anderau et a1 96111 3,325,287 6/1967 Yamamoto et a1961 11 NORMAN G. TORCHIN, Primary Examiner R. E. FIGHTER, AssistantExaminer US. Cl. X.R.

